Replacing R22 with R422D

[hyperion]

We have a customer with several 35year old Dunham Bush chillers curently running on R22. The chiller have Dunham Bush semi hermetic compressors.
They have been advised by a competitor to convert these to R422D. Has anyone any experience of this downgrade/upgrade?
We are concerned about the quantity of R422D to use when compared to R22 and whether or not the performance is going to be reduced as we have read that there can be oil miscibility problems, any thoughts or advice would be much appreciated.
If the upgrade to R422D is not going to be satisfactory, we will be advising to use R22R.
My own thoughts are to leave a 35 year old machine alone, as it is well passed its prime.

[Fri3Oil System]

Hi,

Not only you have to use a higher quantity of refrigerant, but you will have a poorer performance and more serious, a lack of lubricity that could kill compressors.
Check this case study we made on chiller with 2 circuits:
www.fri3oilsystem.com/retrofitcase.zip (http://www.fri3oilsystem.com/retrofitcase.zip)

regards,

Nando.

[Gibbo]

At 35 years old i would think new chillers would be the way to go.
R422D iscan be a bit of a a headache, the refrigerant charge works out to roughly 95% of the R 22 charge.
R422D has smaller smaller molecules and as such has the potential to find a leak where R22 didn't.

If you go to Dupont USA website they will give you all the information on retrofiting. you need
Pay particular attention to the bit about replacing seals and parts in contact with the refrigerant including compressor terminal seals. Also mentions you can have problems with oil return. and what it recommends to do

If you did retrofit you will need to spend more time and attention to the pressure test including standing pressure test for a minimum of 24 hours and probably the same for the vacuum to ensure a leak tight system

With the chillers at the age they are i would stick to R22R and then change out the chillers over the next few years. It will save yourself a few headaches and the customer complaining if it starts leaking after a
few weeks. There may also be problems with oil return in which case Dupont recommend adding some POE oil to ensure oil return.

Last time i looked Dupont didn't have any case studies on chillers with R422D.

If you google R422D you should be able to find articles by Business Edge who retrofited an equally old system some where in the city to R422D and also Trevor Dann of Thermocom did a article on one of their early retrofits.

Good Luck


To be honest it all seems a bit hit or miss to me.

[Gibbo]

Nando

Your link to the case studies on R422D doesn't seem to work.
Can you take a look and resend it.

[Fri3Oil System]

Hi,

it looks we had some troubles with the server which are solved by now. You can download it without problems.
www.fri3oilsystem.com/retrofitcase.zip (http://www.fri3oilsystem.com/retrofitcase.zip)

regards,

Nando

[james10]

Hi, a year ago we carried out a retro fit to a carrier 30hw chiller that also had semi hermetic recips on also it had remote condensors, the original charge of r22 was 350kg and 30l of sunsio 3gs oil. after we had changed head gaskets and valves etc we did a full pressure test and vac test then proceded to charge the system with 350kg of r422d when we ran the system we constantly got lp and oi lpressure trips we contacted dupont who said what we had done was correct and that the problems where elsewhere. back to square one, we checked eveything and found all as should be eventually dupont came to site and drew a blank.
in the end we called in the senior tech the first thing he had us do was change the oil from mineral to ester as r422d is 74% R134a that cured the oil problems then the lp trips we added further refrigerant in total the charge went from 350kg to 750kg now the chillers are running but it definately wasn,t worth the expense and headache i would really make the customer consider replacing the units its a lot of money to spend on a system thats 35 years old and probably difficult to get parts for

[Fri3Oil System]

Hi James,

did you measure the cooling capacity and COP of that chiller before and after the retrofit? you would be surprised of the decrease you'd find. Try to do this analyse before and after when you do a retrofit with any procedure, and then choose the proper one.

regards,

Nando.

[james10]

Hi James,

did you measure the cooling capacity and COP of that chiller before and after the retrofit? you would be surprised of the decrease you'd find. Try to do this analyse before and after when you do a retrofit with any procedure, and then choose the proper one.

regards,

Nando.
all the specs were done by Dupont(they recomended the refrigerant) who sold us the refrigerant it was an up and coming thing back then, we did lose around 15% cooling capacity but that was never an issue as the building had 150% standby

[Gibbo]

Thanks Nando for the link it was very informative.

[hyperion]

Thanks to all for the valued responses. I have read up a lot more and if we take on the project will definately be stearing the client towards R22R, albeit short lived. The gas might even out live these old chillers.
Can't be doing with all of the potential leaking problems and the extra hassle of trying to get more money out of the client when the chillers leak.